iPhone dev team releases yellowsn0w 0.9.4 beta unlock

As promised, the iPhone dev team has delivered its first iPhone 3G unlock beta …

Happy 2009, iPhone dudes and dudettes! What can make the New Year more hackishly awesome than a spanking fresh new iPhone unlock? As promised, the iPhone dev-team has delivered its iPhone 3G unlock for the new year.

This unlock allows you to bypass the carrier lock built into the iPhone, which normally limits the kind of SIM you can use with your unit. Once unlocked, you can use any compatible GSM SIM card from any carrier. With an unlocked iPhone, you can travel abroad and buy cheap local SIMs instead of paying exorbitant roaming fees. An unlock also lets you choose the carrier you want instead of being locked into Apple's business deals.

As we have mentioned before, in the US, the iPhone's GSM standard means you're pretty much limited to AT&T, T-Mobile and a few minor carriers. What's more, using a T-Mobile account will limit your data connection to EDGE only. This is because T-Mobile uses different 3G frequency ranges that the iPhone cannot pick up. Overseas, unlocking offers far more flexibility, depending on the country of use.

Getting started with the 3G unlock

In order to unlock a 3G iPhone, you'll need to upgrade your iPhone to baseband 02.28.00. This is the baseband that ships with the latest 2.2 firmware update from Apple. It's also the baseband and update that the dev team have been warning you not to upgrade to. It turns out that the team eventually managed to unlock the latest and greatest baseband release, so in the words of Emily Litella of Saturday Night Live fame, regarding that whole "don't upgrade to 2.2" thing? Er, never mind. The 3G unlock works exclusively with this latest 02.28.00 baseband.

The unlock software is called yellowsn0w. It is currently in beta and the release version is 0.9.4. Like all beta software, you are warned that this is not a fully-stable final release. The yellowsn0w application must be run from a pwned jailbroken phone. It works by launching a payload injector at boot time. The payload injector checks to see whether the baseband has been reset. If so, it then updates the baseband to an unlocked state. As this software runs as a launch daemon, there's no GUI involved. What's more, you can uninstall the software any time you like.

You can install yellowsn0w directly from Cydia. Reboot your iPhone after install, with the third-party SIM inserted. The team writes, "Wait for the slide to unlock screen, then wait 10 or 15 secs more. If you don’t see your carrier name pop up, then remove your SIM, reinsert it, and wait 10 secs more. This is the step we’ll be working on eliminating next."

Things you need to know about

According to the dev team, there are known issues with SIM Application Toolkit (STK) SIM cards. STK SIMs, which are cards that offer application menus (typical items include "top up," "get credit," and so forth), may have to be ejected and re-inserted after reboot.

Yellowsn0w is an open source release. A link to the software tarball is available on the dev team page. The team emphasizes that the work is completely non-commercial and you should avoid any parties that offer to sell it to you. The dev team does not accept donations at this time, but I bet they'd be pleased as punch should you donate money to a worthy charity in their name.